i access my server through sshd using putty but after a certain period of time the port on which sshd is open is closed automatically. i am not able to figure out this problem. please help me thanks in advance

Typically programs have a version command line option to print the version number. Try running ‘program -v’ or ‘program –version’. Some binary files on your system are actually a link to a specific version of that program. For example, on my system, /usr/bin/python is a link to python-2.7, so I know that I have python version 2.7. (to see if a file is a link run ‘ls -l /path/to/file’ and it will have a ‘l’ at the beginging of the line, and have an arrow at the end followed by the file that the link points to).